Cannula for receiving surgical instruments

ABSTRACT

A cannula ( 10 ) receives surgical instruments ( 120 ) for performing a surgical procedure on a body ( 130 ). The cannula ( 10 ) comprises a tube structure ( 12 ) defining a passage ( 16 ) through which the surgical instruments ( 120 ) are inserted into the body ( 130 ). The tube structure ( 12 ) has a proximal end ( 20 ) and a distal end ( 62 ). The tube structure ( 12 ) includes an expandable portion ( 40 ) for enabling an increase in the cross-sectional area of the passage ( 16 ) at the distal end ( 62 ). The expandable portion ( 40 ) of the tube structure ( 12 ), when expanded, has a conical configuration.

PRIORITY INFORMATION

This application is a continuation of U.S. application Ser. No.09/772,605 filed Jan. 30, 2001, now U.S. Pat. No. 6,800,084, which is acontinuation-in-part of U.S. application Ser. No. 09/137,335, filed Aug.20, 1998, now U.S. Pat. No. 6,187,000.

TECHNICAL FIELD

The present invention is directed to a cannula for receiving surgicalinstruments for performing a surgical procedure on a body.

BACKGROUND OF THE INVENTION

Endoscopic surgical techniques allow a surgical procedure to beperformed on a patient's body through a relatively small incision in thebody and with a limited amount of body tissue disruption. Endoscopicsurgery typically utilizes a tubular structure known as a cannula whichis inserted into a small incision in the body. The cannula holds theincision open and serves as a conduit extending between the exterior ofthe body and the local area inside the body where the surgery is to beperformed.

Due to the relatively small size of the passage into the body which isdefined by the cannula, certain surgical procedures, such as posteriordisectomies and procedures using steerable surgical instruments, havebeen difficult to perform using endoscopic techniques.

SUMMARY OF THE INVENTION

The present invention is a cannula for receiving surgical instrumentsfor performing a surgical procedure on a body. The cannula comprises atube structure defining a passage through which the surgical instrumentsare inserted into the body. The tube structure has a proximal end and adistal end. The tube structure includes an expandable portion forenabling an increase in the cross-sectional area of the passage at leastat the distal end.

The expandable portion of the tube structure, when expanded, has aconical configuration. The expandable portion of the tube structureincludes an arcuate slot and a guide pin disposed in the arcuate slot.The guide pin is movable from a terminal end of the slot to a secondterminal end of the slot to enable the cross-sectional area of thepassage at the distal end to increase.

The tube structure includes first and second tubular portions attachedto one another. The second tubular portion comprises the expandableportion. The first tubular portion comprises a length of stainless steeltubing and the second tubular portion comprises an arcuate segment ofstainless steel sheet stock rolled into a tubular shape.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the present invention will becomesapparent to one skilled in the art to which the present inventionrelates upon consideration of the following description of the inventionwith reference to the accompanying drawings, wherein:

FIG. 1 is an exploded perspective view of a surgical cannula constructedin accordance with the present invention, the cannula being shown in anexpanded condition;

FIG. 2 is a perspective view of the cannula of FIG. 1 with parts removedfor clarity, the cannula being shown in a contracted condition;

FIG. 3 is a schematic end view showing the cannula of FIG. 1 in theexpanded position;

FIG. 4 is a roll out view of a part of the cannula of FIG. 1; and

FIG. 5 is a schematic sectional view of the cannula of FIG. 1 during asurgical procedure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention is directed to a cannula for receiving surgicalinstruments for performing a surgical procedure on the body of apatient. The present invention is applicable to a variety of surgicalprocedures in which endoscopic surgical techniques are used.

FIG. 1 illustrates a cannula 10 constructed according to the presentinvention. The cannula 10 is a tubular structure 12 centered on an axis14. The tubular structure 12 defines a passage 16 through the cannula10. Surgical instruments are inserted into the body during endoscopicsurgery through the passage 16.

The tubular structure 12 comprises a first tubular portion 20 and asecond tubular portion 40 attached to the first tubular portion. Thefirst tubular portion 20 is preferably made of a length of stainlesssteel tubing, but could alternatively be made of another suitablematerial. The first tubular portion 20 has a proximal end 22 and adistal end 24. Parallel cylindrical inner and outer surfaces 26 and 28,respectively, extend between the ends 22, 24 of the first tubularportion 20. The inner surface 26 defines a first passage portion 30 ofthe passage 16 through the cannula 10. The first passage portion 30 hasa diameter D1 which is preferably in the range from 10 mm to 20 mm.

The second tubular portion 40 of the tubular structure 12 is attached tothe distal end 24 of the first tubular portion 20. The second tubularportion is preferably made from stainless steel, but could alternativelybe made from another suitable material.

As best seen in the rollout view of FIG. 4, the second tubular portion40 comprises an arcuate segment 42 of sheet stock. The arcuate segment42 includes first and second arcuate edges 44 and 46, respectively, andfirst and second planar edges 48 and 50, respectively. The first andsecond planar edges 48 and 50 are rolled in an overlapping manner toform the tubular configuration of the second tubular portion 40.

When the second tubular portion 40 has been rolled into its tubularconfiguration, the first and second arcuate edges 44 and 46 defineoppositely disposed first and second ends 60 and 62 (FIGS. 1 and 2),respectively, of the second tubular portion. The first and second ends60 and 62 are connected by a central portion 64. The first end 60 of thesecond tubular portion 40 is attached to the distal end 24 of the firsttubular portion 20 by a single fastener, such as a rivet 66. The rivet66 extends through two aligned apertures 68 (FIG. 4) at the first end 60of the second tubular portion 40. The first end 60 of the second tubularportion 40 is pivotable about the rivet 66.

The second tubular portion 40 includes parallel inner and outer surfaces70 and 72 (FIGS. 1 and 2), respectively, extending between the first andsecond ends 60 and 62. The inner surface 70 defines a second passageportion 74 of the passage 16 through the cannula 10 which extends as acontinuation of the first passage portion 30 in the first tubularportion 20.

An arcuate slot 80 is formed in the second tubular portion 40 andextends between the inner and outer surfaces 70 and 72 of the secondtubular portion. The arcuate slot 80 extends along a curvilinear path inthe central portion 64 of the second tubular portion 40 toward thesecond end 60 of the second tubular portion. The arcuate slot 80 has afirst terminal end 82 located in the central portion 64 of the secondtubular portion 40. A second terminal end 84 of the arcuate slot 80 islocated adjacent the intersection of the second arcuate edge 46 and thefirst planar edge 48 of the arcuate segment 42.

A guide pin 90 is attached to the inner surface 70 of the second tubularportion 40 adjacent the intersection of the second arcuate edge 46 andthe second planar edge 50. In the tubular configuration of the secondtubular portion 40, the guide pin 90 is located in the arcuate slot 80and is movable along the curvilinear path of the arcuate slot. A washer92 is secured an inner end of the guide pin 90 to retain the guide pinin the arcuate slot 80.

The second tubular portion 40 of the tubular structure 12 is expandablefrom a contracted condition shown in FIG. 2 to an expanded conditionshown in FIG. 1. In the contracted condition, the guide pin 90 islocated in the first terminal end 82 of the arcuate slot 80 in thesecond tubular portion 40 and the second passage portion 74 defined bythe second tubular portion is cylindrical in shape. The second passage74 has a generally constant diameter D2 (FIGS. 2 and 3) which isapproximately equal to the diameter D1 of the first tubular portion 20.Thus, the cross-sectional area of the second passage portion 74 at thesecond end 62 of the second tubular portion 40, which is function of thediameter D2, is approximately the same as the cross-sectional area atthe first end 60 of the second tubular portion and is approximately thesame as the cross-sectional area of the first passage portion 30 in thefirst tubular portion 20.

In the expanded condition, the guide pin 90 is located in the secondterminal end 84 of the arcuate slot 80 in the second tubular portion 40and the second tubular portion has a conical configuration. At thesecond end 62 of the second tubular portion 40, the second passageportion 74 has a diameter D3 (FIG. 3) which is larger then the diameterD2 of the second passage portion at the first end 60. Preferably, thediameter D3 of the second passage portion 74 at the second end 62 of thesecond tubular portion is 40% to 80% greater than the diameter D1 of thesecond passage portion at the first end 60. Thus, in the expandedcondition, the cross-sectional area of the second passage portion 74 atthe second end 62 of the second tubular portion 40, which is function ofthe diameter D3, is 40% to 80% greater than the cross-sectional area ofthe second passage portion at the first end 60 of the second tubularportion.

The cannula 10 includes an outer layer 100 (FIG. 1) for maintaining thesecond tubular portion 40 of the cannula in the contracted condition. Itis contemplated that other suitable means for maintaining the secondtubular portion 40 in the contracted condition could be employed. Inaccordance with a preferred embodiment of the present invention, theouter layer 100 comprises a section of plastic tubing 102 which is heatshrunk over both the first and second tubular portions 20 and 40 to holdthe second tubular portion in the contracted condition.

In addition, a loop of nylon string 104 for tearing the heat shrunktubing 102 is wrapped around the heat shrunk tubing so that it extendsboth underneath and on top of the tubing. An outer end 106 of the string104 extends beyond the tubing 102.

The cannula 10 further includes an actuatable device 110 for expandingthe second tubular portion 40 from the contracted condition to theexpanded condition. In accordance with a preferred embodiment of thepresent invention, the actuatable device 110 comprises a manuallyoperated expansion tool 112. The expansion tool 112 resembles a commonpair of scissors and has a pair of legs 114 pivotally connected to oneanother. The expansion tool 112 includes a frustoconical end section 116formed by a pair of frustoconical halves 118. Each of the frustoconicalhalves 118 extends from a respective one of the legs 114 of theexpansion tool 112. It is contemplated that other suitable means forexpanding the second tubular portion 40 toward the expanded conditioncould be employed, such as an inflatable balloon (not shown).

During an endoscopic surgical procedure, the cannula 10 is inserted intothe body of a patient in the contracted condition. The outer end 106 ofthe string 104 is then manually pulled on by the surgeon. Pulling on thestring 104 tears the heat shrunk tubing 102 which is then removed fromthe cannula 10 by the surgeon. With the heat shrink tubing 102 removed,the second tubular portion 40 of the cannula 10 is thereby released forexpansion toward the expanded condition.

Next, the expansion tool 112 is inserted into the passage 16 in thecannula 10 until the frustoconical end section 114 is located at thesecond end 62 of the second tubular portion 40. The legs 114 of theexpansion tool 112 are manually separated, causing the frustoconicalhalves 118 to separate also. As the halves 118 separate, a radiallyoutward directed force is exerted on the inner surface 70 of the secondtubular portion 40 by the halves 118, causing the second tubular portionto expand toward the expanded condition. Under the force of theexpanding expansion tool 112, the guide pin 90 slides from the firstterminal end 82 of the arcuate slot 80 to the second terminal end 84 ofthe arcuate slot to permit the expansion of the second tubular portion40. The expansion tool 112 can be rotated about the axis 14 to ensurethat the second tubular portion 40 of the cannula 10 is completelyexpanded to the expanded condition. The expansion tool 112 is thencollapsed and removed so that one or more surgical instruments(indicated schematically at 120 in FIG. 5) can be received through thecannula 10 and inserted into a patient's body 130.

The expandable second tubular portion 40 of the cannula 10 provides asignificantly larger working area for the surgeon inside the body 130within the confines of the cannula. As a result, the simultaneous use ofa number of endoscopic surgical instruments, including but not limitedto steerable instruments, shavers, dissectors, scissors, forceps,retractors, dilators, and video cameras, is made possible by theexpandable cannula 10.

It is contemplated that the cannula 10 described herein could be thecenterpiece of a endoscopic surgical kit which would include anassortment of surgical instruments designed and/or selected for use withthe cannula.

From the above description of the invention, those skilled in the artwill perceive improvements, changes and modifications. Suchimprovements, changes and modifications within the skill of the art areintended to be covered by the appended claims.

1. An apparatus for providing access to a spinal location within apatient, comprising: an elongate body having a proximal end and a distalend and defining a length between the proximal and distal ends such thatthe proximal end can be positioned outside the patient and the distalend can be positioned inside the patient adjacent the spinal location,said elongate body having an outer surface and an inner surface, saidinner surface defining an access path, said elongate body beingexpandable from a contracted configuration to an expanded configuration,wherein the cross-sectional area of said body at a first location isgreater than the cross-sectional area of said body at a second locationin the expanded configuration, wherein the first location is distal tothe second location; an arcuate slot having an elongate length, a firstend and a second end along which a portion of the elongate body ismoveable from its contracted condition to its expanded condition, thearcuate slot extending generally in the direction of expansion betweenthe contracted and expanded conditions; and a guide member movablewithin the arcuate slot, the guide member moving along the arcuate slotas the elongate body moves from its contracted condition to its expandedcondition, wherein the access path is sized such that more than onesurgical instrument can be advanced simultaneously along the access pathbetween the proximal end and the spinal location.
 2. The apparatus ofclaim 1, wherein the elongate body comprises a first member and a secondmember moveable relative to each other.
 3. The apparatus of claim 1,wherein the elongate body in the contracted configuration issubstantially tubular having a substantially circular cross-section. 4.The apparatus of claim 1, wherein the elongate body comprises sheetmetal material.
 5. The apparatus of claim 4, wherein the elongate bodyis made of stainless steel.
 6. The apparatus of claim 1, wherein thedistal end is configured to be inserted through an incision in the backof a patient.
 7. An apparatus for providing access to a spinal locationwithin a patient, comprising: an elongate body having a proximal end anda distal end and defining a length between the proximal and distal endssuch that the proximal end can be positioned outside the patient and thedistal end can be positioned inside the patient adjacent the spinallocation; the elongate body having at least first and second sides andbeing expandable such that a transverse dimension extending between thefirst and second sides of the elongate body at a first location isgreater than a transverse dimension extending between the first andsecond sides of the elongate body at a second location, wherein thefirst location is distal to the second location and the elongate bodyprovides an access path to the spinal location between the first andsecond sides; a guiding mechanism comprising a curved elongate slotextending in a generally transverse direction along which a portion ofthe elongate body is moveable from its contracted condition to itsexpanded condition; and a guide pin movable within the curved elongateslot, the guide pin moving along the slot as the elongate body movesfrom its contracted condition to its expanded condition, wherein theaccess path is sized such that more than one surgical instrument can beadvanced simultaneously along the access path between the proximal endand the spinal location.
 8. The apparatus of claim 7, wherein at leastone of the first and second sides comprises a metal portion.
 9. Theapparatus of claim 7, wherein at least one of the first and second sidescomprises a substantially smooth metal surface facing said access path.10. The apparatus of claim 7, wherein the elongate body comprises aproximal portion and a distal portion coupled with the proximal portion.11. The apparatus of claim 7, wherein the elongate body is substantiallytubular having a substantially tubular cross-section at least when notexpanded.
 12. The apparatus of claim 7, wherein the distal end isconfigured to be inserted through an incision in the back of a patient.